Electric arc light source having undercut recessed anode



Sept. 23, 1969 D. G. VAN ORNUM ETAL 3,469,143

ELECTRIC ARC LIGHT souncm mwme UNDERCUT macasssn mom;

Original Filed April 29, 1965 2 Sheets-Sheet 1 WMWSQW Sept. 23, 19 69 VAN QRNUM ET AL 3,469,143

UNDERCUT RECESSED ANODI';

ELECTRIC ARC LIGHT SOURCE HAVING 2 Sheets-Sheet 2 Original Filed April 29, 1965 m V v 22 l I I, l 1 1 I DELBEQT WILL/HM United States Patent M 3,469,143 ELECTRIC ARC LIGHT SOURCE HAVING UNDERCUT RECESSED ANODE Delbert G. Van Ornum, Newport Beach, and William A. Geideman, Jr., Santa Ana, Calif., and Kurt Muller, Baden, Switzerland, assignors to Geotel Inc., a corporation of Delaware Continuation of application Ser. No. 453,241, Apr. 29, 1965. This application Oct. 11, 1966, Ser. No. 585,988 Int. Cl. H01j 7/24 US. Cl. 315-111 12 Claims ABSTRACT OF THE DISCLOSURE A gas vortex-stabilized radiation source in which one of the electrodes has a mouth formed therein. The mouth has a lip through which the arc passes, the arc seating on the bottom wall of the mouth.

This application is a continuation of patent application Ser. No. 453,241, filed Apr. 29, 1965, for Electric Arc Light Source Having Undercut Recessed Anode, now abandoned.

The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42 U.S.C. 2457).

This invention relates to a light or radiation source of the type wherein the light emanates from a highcurrent electric are. More particularly, the invention relates to a vortex-stabilized radiation source characterized by high efficiency and are stability, long electrode life at high power levels, readily-controllable emission, and other important advantages.

One form of such a radiation source is described and claimed in a co-pending United States patent application Ser. No. 437,963 for an Electric Arc Light Source and Method, inventor Delbert G. Van Ornum. In the light source described in the indicated patent application, the anode is provided with a recess adapted to receive one end portion of the electric arc.

An object of the present invention is to provide a light or radiation source of the recessed-anode type, and wherein the recess is undercut in order to increase the diffusion of the arc in the region of the anode footpoint, thus increasing the current-carrying capabilities of the source.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE 1 is a view, primarily in longitudinal section, of a radiation source constructed in accordance with the present invention;

FIGURE 2 is a fragmentary transverse sectional view on line 22 of FIGURE 1;

FIGURE 3 is a section on line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged view of the central portion of the showing of FIGURE 1;

FIGURE 5 is a transverse section on line 55 of FIGURE 4;

FIGURE 6 is a section on line 6-6 of FIGURE 4;

FIGURE 7 is a sectional view along line 7-7 of FIG- URE 4; and

FIGURE 8 is a fragmentary sectional view on line 8-8 of FIGURE 7.

Referring first to FIGURE 1, the illustrated apparatus comprises first and second metal body elements 10 and 11 comprising flanges -12 and 13 on stems 14 and 15, respectively. Extended between the flanges 12 and 13 is a Patented Sept. 23, 1969 relatively large-diameter tubular outer envelope 16 which may be formed of quartz, fused silica, or other suitable transparent material. Extended between the opposed inner end portions of the stems 14 and 15, in coaxial relationship relative to outer envelope 16, is a tubular inner envelope 17 which may be formed of the same material. Envelopes 16 and 17 define between them an annular outer chamber 18 into which gas is introduced as will be indicated subsequently, such chamber being maintained sealed from the chamber defined within inner envelope 17 by suitable O-rings 19 or other seals. The chamber defined within envelope -17, between the opposed inner ends of stems 14 and 15, is the arc chamber and has been given the reference number 20.

Proceeding next to a preliminary description of the stem 14, the cylindrical main body of such stem (which is coaxial with both chambers 18 and 20) is provided with a central chamber or bore indicated at 22. The inner end of the stern, radially outwardly of bore 22, is shaped exteriorly as a frustoconical surface 23, such surface being one of the end surfaces of the anode element of the present construction. The frustoconical surface 23 is shown as merging with a radial surface 24 which lies in a plane perpendicular to the common axis of chambers 18 and 20. The remaining and highly important components of the anode (formed by the inner end of stem 14, and by associated parts) will be described hereinafter, after a description of the associated cathode, power means, gasflow means, and cooling means.

The stem 15, which normally forms the cathode of the apparatus, may be shaped with the illustrated conical inner end portion 26 which is coaxial with the common axis of chambers 18 and 20. The base of the conical exterior surface of end 26 merges with a radial surface 27 which is perpendicular to such common axis. The region radially-outwardly of the base of cone 26 receives relatively cool gas which is delivered thereto through passages or conduits 28, such passages being oriented (as will be described) to effect a strong vortical flow of gas in arc chamber 20 about the axis thereof. Gas enters the passages 28 from an annular groove 29 which is formed in stem 15 adjacent one end of envelope 17.

The gas-inlet passages 28 to are chamber 20 are best shown in FIGURES 4, 7 and 8. Such passages extend in a direction toward the interior surface of inner envelope 17, so that the inflowing gas will cool and clean such envelope. Thus, the ends (inner) of passages 28 which directly com- :munieate with chamber 20 are shown as being located adjacent the junction of surface 27 with the conical surface of element 26. The remaining (outer) ends of the passages, which communicate with annular groove 29, are disposed closer to the axis of the apparatus, so that the above-indicated direction of gas flow toward envelope 17 results,

As best shown in FIGURE 8, the passages 28 not only extend toward envelope 17 but, much more importantly, extend in a direction which is generally tangential to the axis of chamber 20, so that the necessary vortical or helical gas flow is achieved. Preferably, a substantial number of inlet passages 28 are provided, four such passages being illustrated in FIGURE 7. Passages 28 are identical to each other, and are spaced degrees apart.

Each of the passages 28 is inclined at an acute angle (shown as 45 degrees, FIGURE 8) to a plane containing the axis of the light source, in such relationship that the gas flow in chamber 20 will be smoothly helical in nature. This produces benefits including increasing arc stability, and decreasing the gas pressure drop, through chamber 20.

The gas which is delivered to the annular groove 29, and thus through passages 28 to are chamber 20, is supplied to annulus 18 (FIGURE 1) through one or more inlet 3 passages indicated at 31 in FIGURES 1-3. Passage 31 is oriented in such manner as to eifect a helical flow of gas in the annulus 18 between envelopes 16 and 17, the gas spiraling longitudinally along envelope 18 and then entering the annular groove 29.

Gas is supplied to the inlet passage or passages 31 through a recirculation conduit 32 in which are interposed a suitable pump 33 and heat exchanger 34. The heat exchanger 34 effects cooling of gas which discharges from are chamber 20 through the anode, by means of passages and conduits to be described hereinafter.

The cathode 26 is water cooled in a suitable manner. For example, as shown in FIGURES 1 and 4, the stem 15 may be formed with a longitudinal passage or opening 36 into which is inserted a water-inlet conduit 37. Water introduced through conduit 37 impinges against the apex portion of the cathode cone 26, and then flows outwardly (radially around conduit 37) for discharge through an outlet 38.

A suitable current source 39, preferably adapted to deliver a very high current, is connected between the elements and 11 (which are formed of copper or other highly conductive material) by means of leads 41 and 42. A starter circuit, indicated schematically at 43, may be interposed in one of the leads (for example, number 42) in order to initiate the discharge between the electrodes. The starter circuit may include means to create a momentary high-voltage or high-frequency pulse discharge.

The current source 39 should be a DC. source having the positive terminal thereof connected to element 10, so that the inner end of stem 14 serves as the anode as previously indicated. It is to be understood, however, that reverse polarity may be employed if desired. It is also to be understood that various other current sources, for example A.C. sources, pulse sources, etc., may be employed if desired.

DETAILED DESCRIPTION OF THE ANODE ASSEMBLY Stated generally, the anode is provided with a recess or opening 45 which is coaxial with the arc chamber 20, the bottom of the recess (at least in the vicinity of the axis of arc chamber 20) being closed.

Stated more definitely, the recess 45 has an annular wall 47 (FIGURE 4), such annular wall including a relatively large-diameter cylindrical portion 47a, and a relatively small-diameter cylindrical portion 47b. Portion 47b is relatively adjacent cathode 26, and forms the lip or mouth portion of the wall means defining recess 45. Stated otherwise, lip portion 47b defines the mouth or opening through which chamber 45 communicates with are chamber 20.

The bottom of recess 45 is shown as comprising a wall 48 lying generally in a radial plane. Such wall forms the arcing surface of the anode, the electric are extending therefrom through the opening defined by annular wall portion 47b, and along the axis of the arc chamber to the tip of cathode cone 26. Chamber or recess 45 may be termed the foot chamber, since arc 49 seats or foots therein.

The wall portion 47b should have a diameter substantially larger than that of the arc portion within chamber 20. The base or foot region of the arc, within recess 45, fans or spreads out to a diameter larger than that of wall portion 4711. Thus, the current density at arcing surface 48 is reduced, and the life of the anode increased accordingly.

The arcing bottom wall 48 of recess 45 should be sufficiently close to are chamber 20, namely to radial surface 24 in the illustrated configuration, that light emanating from the center of wall 48 will be transmitted in a generally radial direction (as Well as an axial direction), as indicated by the phantom lines 51 in FIGURE 4.

Gas-discharge passages communicate with the recess 45 at the periphery of the arcing wall 48. A plurality of such gas-discharge passages should be provided, in spaced relationship around the recess. Thus, in the illustrated form, three such passages or conduits 46 are shown. The three passages 46 have radially-extending nozzle portions 52- 54 (FIGURE 6) which intersect the wall 47 of the recess 45. Such radially-extending nozzle portions 52-54 communicate with the main portions of passages 46, the latter extending in inclined manner through a cooling (heat transfer) section of the anode as will be described hereinafter.

The described provision of an arcing electrode portion 48 through which gas does not discharge, in combination with the peripherally-located gas discharge means 52-54, and further in combination with the annular element 47, provide major advantages relative to such factors as power capability, efficiency, emission characteristics, electrode life, etc. It is emphasized, however, that a substantial factor relative to the present light source and method relates to the manner of cooling the walls of recess 45 to provide a heat-sink action which combines with the pressure-sink action effected by passages 46.

Proceeding next to a description of the cooling means, and to a further description of the gas-discharge means, the stem 14 of the anode is provided with a solid, reentrant portion 56 having a cylindrical peripheral wall 57 coaxial with the axis of the stem 14 and of the chamber 22 therein. The base of re-entrant portion 56, that is to say the inner end of the chamber 22, is located in spaced relationship from anode surfaces 23 and 24, generally radially-outwardly of the bottom wall 48 of recess 45. There are thus formed large cross-sections through which heat may be transferred from the walls of recess 45 to the inner end of chamber 22.

A metal tube 58 is connected to (or integral with, as shown) the end of re-entrant portion 56, and extends axially of chamber 22 for connection to the conduit 32 through which the gas recirculates. Each of the gas-outlet passages 46 communicates with the passage formed in tube 58.

A water-separator tube or conduit 59, having a diameter substantially larger than that of tube 58, extends into the chamber 22 into telescoped relationship with re-entrant portion 56. The inner diameter of the water separator tube is slightly larger than the diameter of wall 57, so that an annular gap 61 is provided as shown in FIG- URE 4 (such gap being so small as to prevent illustration thereof in FIGURE 1).

The annulus 62 between tubes 58 and 59 communicates with a plurality of angularly-shaped coolant passages 63- 65 having corner or elbow portions disposed adjacent the arcing bottom wall 48 of recess 45. Such passages 63-65 not only have inlet ends communicating with annulus 62 but also have outlet ends communicating with chamber 22 radially-outwardly of water-separator tube 59.

Water is introduced into the annulus 62 by means of an inlet conduit 66 (FIGURE 1), and flows to the right through such annulus (FIGURES 1 and 4) to effect a certain amount of cooling of the gas which passes outwardly through tube 58. Upon reaching the inner end of annulus 62, the water separates, one portion flowing through the annular gap 61 (FIGURE 4) and the other portion flowing through the elbow-shaped passages 63- 65. The water then flows to the left, through the annulus which is defined radially-outwardly of water separator 59 and within the chamber 22, for discharge through an outlet conduit 67.

In the described manner, relatively cool Water is delivered to the region surrounding the base of re-entrant anode portion 56, and is also delivered directly (through passages 63-65, FIGURE 5) to the region adjacent the arcing wall 48 of the anode. This effects an extremely efiicient cooling of all wall portions of recess 45. In addition, the walls of the gas-discharge passages 46 are effectively and efiiciently cooled. In the latter connection it is pointed out that the number of gas-discharge passages 46 is preferably equal to the number of water passages 63-65, and that such passages are offset (as shown in FIGURE 5) so that one gas passage lies between each two adjacent water passages. The amount of heat transfer from the gas-discharge passages to the water is thus comparable to the heat transfer from the walls of recess 45 to the water.

OPERATION In the operation of the present light source, the entire system is filled with the desired inert gas, following which the pump 33 is started to commence gas recirculation. Starter 43 is then employed to initiate the are 49. The vertically-flowing gas in chamber 20 then effectively stabilizes the arc, and constricts the same to a smaller cross-sectional area than it would normally occupy in space.

It is pointed out that the recirculating gas discharges from arc chamber 20 (not recess 45) through an axial opening (namely, recess 45) in one of the electrodes (the anode). However, such axial opening is relatively large in diameter and, furthermore, is not a continuous straight gas-outlet conduit but instead has a bottom arcing wall 48 which prevents discharge of gas along the exact axis of the recess. Thus, the arc does not extend into the gasdischarge passages 46 but instead foots on the wall 48. Furthermore, and very importantly, the arc spreads after entering the recess 45 (through the mouth defined by wall portion 47b) to provide a generally conical footing region 68 (FIGURE 4) which merges with the generally cylindrical main body of the are 49. Such spreading of the arc over the majority of the area of arcing wall 48 reduces current density at the electrode, greatly increases electrode life, and changes the emission characteristics of the are as will be indicated hereinafter. Because the diameter of wall portion 47b is less than that of portion 47a, the degree of spreading (and consequent decreased current density) is very substantial.

The gas discharges from the chamber 20 at a region adjacent the arc and also relatively adjacent the axis of the arc chamber, as is required for eflicient vortex action in a radiation source. However, the gas does not discharge from the recess 45 along the axis thereof but instead in the generally radially-outward direction through the nozzle portions 52-54 of the gas-discharge passages 46. Because of the fact that the arc does not extend into such passages, and because of the efficient water cooling of such passages as described above, there is only a very small amount of erosion of the passage Walls.

The annular wall portion 47b of the recess or opening, although relatively large in comparison with prior-art constructions of the type wherein the gas discharges through a long axial passage or conduit, has been found to produce a surprising degree of arc stabilization and constriction. As indicated above, the diameter of wall portion 47b is caused to be sufficiently large to permit efiicient transmission of light from arcing surface 48, and sufiiciently large that the electrode will not melt or erode excessively at surface 47, but sufiiciently small to efiect the desired degree of constriction and stabilization of the arc 49.

Because there is no substantial axial opening in arcing wall 48, the gas present within the hot core of the are 49 is relatively stagnant. Such gas being relatively stagnant, it may be maintained in an extremely hot, highly-excited condition with a minimum of energy. Stated in another manner, observation of the arc indicates that only a small portion of the gas moving through the exhaust holes 52-54 is directly arc heated, most of the exhaust gas coming instead from the partially-excited gas around the arc column 49. The result is a significant increase in the efficiency of the radiation source.

It is emphasized that, for a given pressure in the main body of arc chamber 20, the pressure at the aXis of such chamber is substantially higher in the present source than in constructions wherein the gas discharge is through a straight passage along the axis. Stated otherwise, the gas pressure along the axis of chamber 20 is maintained relatively high because the gas is relatively stagnant at such axis, instead of being continuously drained. The resulting high pressure along the axis is distinctly desirable relative to such factors as radiation characteristics and efiiciency,

A further important result of the relatively stagnant gas which is present within the arc core 49 is that there is an extremely conductive path between wall 48 and the arcing apex of cathode 26. Such conductive path, the relatively stagnant hot gas within the base portion 68 of the arc, the large area of arcing portion 48 of the anode, and other factors, operate to cause the voltage drop between anode and cathode to be low in comparison to prior-art structures. Thus, for a given power input, the current is relatively high and the voltage relatively low. Because light emission depends largely upon current as distinguished from voltage, the luminous efiiciency of the present light source is extremely high.

The gas employed in the present radiation source should be a noble gas such as (for example) argon, neon, krypton, xenon, or mixtures thereof, at high pressures. The gas pressure within arc chamber20 should be on the order of hundreds of pounds per square inch.

It has been found that maximum stability of the arc is achieved when the diameter of the cylindrical body of the arc (in chamber 20) is in the range of about onethird to two-thirds of the diameter of portion 47b of wall 47. The diameter of such cylindrical portion of the arc should not be as large as that of wall portion 47b.

It is pointed out that the cathode 26 of the present source is (like the anode) devoid of gas-outlet passages along the axis of the arc chamber. Thus, the stagnant gas condition along the axis is maintained.

The tip of the cathode may be formed of thoriated tungsten, and should be operated at or near the melting point. The bottom wall 48 of the recess 45 may be for-med of tungsten, which should also be at a temperature near the melting point. a

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

We claim:

1. Apparatus for generating high-intensity light, which comprises:

wall means to define an arc chamber,

at least a portion of said wall means being transparent, wall means to define a foot chamber communicating through an opening with said arc chamber,

said last-named wall means including a relatively small-diameter lip portion adjacent said are chamber and defining said opening,

said last-named wall means further including a relatively large-diameter portion on the opposite side of said lip portion from said are chamber,

means to form an arcing surface in said foot chamber, an electrode having an arcing portion disposed in said arc chamber opposite said opening,

means to effect a high-current electrical discharge between said arcing surface and said arcing portion of said electrode,

means to introduce gas into said arc chamber and to effect vortical flow of said gas about an axis which extends through said opening to said arcing portion of said electrode, and

means to discharge said gas from said arc chamber through said opening,

said discharge means including gas-outlet means communicating with said foot chamber.

2. Apparatus for generating high-intensity light, which comprises:

wall means to define an arc chamber,

at least a portion of said wall means being transparent, wall means to define a foot chamber communicating through an opening with said are chamber, said last-named wall means including a relatively small-diameter lip portion adjacent said are chamber and defining said opening, said last-named wall means further including a relatively large-diameter portion on the opposite side of said lip portion from said are chamber, means to form an arcing surface in said foot chamber in the region opposite said opening and coaxial with said opening,

said arcing surface being sufficiently close to said opening, and said opening being sufficiently large in diameter, that light generated in at least the center of said arcing surface may be readily transmitted through said transparent wall means, an electrode having an arcing portion disposed in said are chamber opposite said opening, means to effect a high-current electrical discharge between said arcing surface and said arcing portion of said electrode, means to introduce gas into said are chamber and to effect vortical flow of said gas about an axis which extends from said arcing surface through said opening to said arcing portion of said electrode, and means to discharge said gas from said arc chamber through said opening,

said discharge means including gas-outlet means communicating with said foot chamber at the peripheral region thereof. 3. Apparatus for generating high-intensity light, which comprises:

wall means to define an arc chamber,

at least a portion of said wall means being transparent, at least a major portion of said wall means comprising a surface of revolution about a central axis, wall means to define afoot chamber communicating through an opening with said are chamber,

said opening being defined by an annular wall portion coaxial with said central axis, the diameter of said annular wall portion being much smaller than that of said surface of revolution, means to form an arcing surface in said foot chamber coaxially of said central axis and in the region of said foot chamber opposite said opening,

said arcing surface having a diameter substantially larger than that of said annular wall portion, said arcing surface being sufficiently close to said opening, and said annular wall portion being sufficiently large in diameter, that light generated at at least the portion of said arcing surface at said axis may be readily transmitted through said transparent wall portion, an electrode having an arcing portion disposed in said are chamber opposite said opening, means to maintain a high-current electric arc between said arcing surface and said arcing portion of said electrode,

said means being a DC. source having the positive terminal thereof connected to said arcing surface, and the negative terminal thereof connected to said electrode, means to introduce gas at high pressure into said are chamber and to effect vortical flow of said gas in said chamber about said central axis,

said gas-introduction means being independent of said foot chamber and of said opening, and

means to discharge said gas from said are chamber through said opening,

said discharge means including gas-outlet means communicating with said foot chamber.

4. The invention as claimed in claim 3, in which said foot chamber is formed in an electrode incorporating said annular Wall portion and said arcing surface, in which said gas-outlet means includes a plurality of passages the intake portions of which communicate with said foot chamber adjacent said annular wall portion, and in which means are provided to pass coolant continuously through said electrode containing said foot chamber to thereby effect cooling of said arcing surface and the walls of said passages.

5. Apparatus for generating high-intensity light, which comprises:

wall means to define an arc chamber,

at least a portion of said wall means being transparent, said wall means including a surface of revolution about a central axis, means to define a solid, hole-free arcing surface transversely of the axis of said surface of revolution,

means to introduce gas continuously into said chamber and to effect vortical flow of said gas about said axis in said chamber,

means to maintain an electric are along said axis between said arcing surface and an electrode spaced and insulated therefrom,

outlet means located adjacent the region encompassing said arcing surface to continuously discharge said gas from said chamber, and

means to define an annular lip coaxially of said axis and between said arcing surface and said electrode, said annular lip being smaller in diameter than said arcing surface and being sufficiently small in diameter to effect spreading of the portion of said are extending between said arcing surface and said lip, whereby the diameter of said arc at said arcing surface is substantially larger than the diameter of said are at a region between said lip and said electrode, said lip being suffieiently large in diameter to permit transmission of .light from a point lying on said axis and also on said arcing surface and in a direction having a substantial component radial to said axis, said light passing through said transparent wall means to the exterior of said apparatus.

6. The invention as claimed in claim 5, in which outlet means comprises a plurality of passages the intake portions of which are disposed at least as far from said axis as is the portion of said lip which is nearest said axis.

7. Apparatus for generating high-intensity light, which comprises:

light-transmissive wall means to define a chamber a wall of which is a surface of revolution about a central axis,

first and second metal electrodes having end portions disposed in said chamber at spaced points along said central axis,

the end portion of said first electrode having a recess formed therein, the side wall of said recess being annular and coaxial of said axis,

said annular side wall having at the region thereof adjacent said second electrode a lip the diameter of which is smaller than that of the remainder of said annular wall, the bottom wall of said recess being substantially solid and being generally transverse to said axis, means to effect continuous introduction of high-pressure gas into said chamber,

said means being so directed as to effect How of gas vortically in said chamber about said axis, means to efiect continuous discharge of at least a major portion of said gas from said chamber through outlet-opening means the intake portion of which com municates with said recess adjacent said side wall thereof, and a D0. current source having the positive terminal thereof connected to said first electrode and the negative terminal thereof connected to said second electrode,

said source being adapted to maintain a high-current electric are along said axis between said second electrode and said bottom wall of said recess, the light generated by said are being transmitted through said light-transmissive wall means.

8. The invention as claimed in claim 7, in which said current source and said gas-introduction means are so correlated to the diameter of said lip that the portion of said arc in said chamber has a diameter substantially smaller than that of said lip.

9. The invention as claimed in claim 7, in which said end portion of said second electrode is free of substantial gas outlet openings at said axis.

10. Apparatus for generating comprises:

wall means to define an arc chamber,

at least a portion of said wall means being formed of a transparent material,

first and second elongated electrodes having end portions disposed in said chamber,

at least said end portion of said first electrode being hollowed out to form an opening the mouth of which faces said end portion of said second electrode,

said mouth having a lip the diameter of which is smaller than that of the remainder of said mouth, means to maintain a high-current electric arc in said chamber between said electrodes and along a predetermined axis extending through said mouth,

means to introduce gas continuously into said are chamber in a generally tangential direction adapted to effect vortical flow of said gas about said axis, and

means to drain gas continuously from said opening in a direction generally radial to said axis and at a region close to said arc chamber.

11. Apparatus for generating high-intensity light, which comprises:

wall means to define an arc chamber,

high-intensity light, which at least a portion of said wall means being formed 50 of a transparent material, first and second elongated electrodes having end portions disposed in said chamber,

at least said end portion of said first electrode being hollowed out to form an opening the mouth of which faces said end portion of said second electrode,

said mouth having a bottom wall, said mouth also having a lip the diameter of which is smaller than that of the adjacent region of the mouth, the diameter of said lip being sufficiently large that an are maintained between said electrodes will pass through said lip into said mouth and seat on said bottom wall of said mouth, means to maintain a high-current electric arc in said chamber between said electrodes and along a predetermined axis extending through said mouth,

said are extending through said lip and seating on said bottom wall of said mouth, and means to introduce gas continuously into said are chamber in a generally tangential direction adapted to effect vortical flow of said gas about said axis. 12. A method of generating high-intensity light, which comprises:

providing wall means to define a discharge chamber,

at least a portion of said wall means being transparent, providing first and second electrodes having arcing portions communicating with said discharge chamber, said arcing portions being located adjacent spaced points along a predetermined axis, maintaining a high-current electrical discharge in said chamber along said axis and between said arcing portions, effecting continuous introduction of gas into said chamber in such manner that said gas flows vortically therein about said axis, continuously draining gas from said chamber axially thereof through a recess in at least one of said arcing portions,

said one arcing portion having an annular lip at the mouth of said recess and adjacent said discharge chamber, effecting flow of gas in said recess radially outwardly away from said axis and on the opposite side of said lip from said discharge chamber, and transmitting light from said discharge through said transparent portion of said wall means.

References Cited UNITED STATES PATENTS 11/1962 Gage 3315-111X 2/1966 Ducati 315-l11 US. Cl. X.R. 

